The cellular slime molds, an example of which is Dictyostelium discoideum, exist as independent amoeboid cells during their vegetative phase. Eventually aggregation of the amoebae into pseudoplasmodia occurs in response to the chemotactic substance cyclic AMP. Aggregation is followed by a decline in cell division and the differentiation of the amoebae into pretalk and prespore cells. These two types of cells further differentiate into stalks and spores composing the mature sorocarp. The proposed research involves a study of the incorporation of the sugar, 3H-L-fucose into the glycoproteins of Dictyostelium amoebae during growth and differentiation. 3H-L-fucose is incorporated in specific patterns in prespore cells but prestalk cells incorporate negligible quantities. The effects of cyclic AMP and the role of cellular contacts and interactions in the synthesis of glycoproteins will be investigated in order to determine their function during development of Dictyostelium.